The Scifres Nanofabrication Laboratory was built with the flexibility and capability to make new discoveries decades into the future.
Located in the Birck Nanotechnology Center (BNC) at Purdue University, the 25,000 sq. ft. cleanroom combines specialized tools with opportunities for student and faculty research, as well as a process for training outside engineers and scientists to use the facility.
Purdue University celebrated a decade of research advancements in nanotechnology at an Oct. 30 event that marked the tenth anniversary of the opening of the $58 million Birck Nanotechnology Center. The facility supports over 400 users, including both the cleanroom and the laboratories.
The diverse user base of the BNC cleanroom, which serves all the engineering and science departments from across campus, in addition to pharmacy, has caused a unique blending of technologies and a broad range of research groups.
“One thing we’re observing over time is a convergence of science, engineering, and biological disciplines,” says Ali Shakouri, the Mary Jo and Robert L. Kirk Director of Birck Nanotechnology Center and a professor of electrical and computer engineering. “Our facility provides a key enabling capability to support leading-edge research in any or all of these disciplines.”
Recently, while a mechanical engineering group was looking at the properties of microscopic graphene, a biological group found that this new material had extreme sensitivity to various biological activations. This discovery is now leading to the development of new biological sensors for a variety of human conditions, including the ability to sense sugar levels in diabetic patients without the need for a blood sample.
“We build on our strengths and then make sure that those strengths result in a significant impact both for the state of Indiana and globally,” says Suresh Garimella, Executive VP for Research and Partnerships.
Assisting the convergence of disciplines is the ability for researchers to access both the particle-free environment needed for fabricating microscale and nanoscale devices, as well as the biological-pharmaceutical-grade environment needed for work with biological nanotechnology.
The BNC cleanroom was one of the first to specially link these two cleanroom types. While they both exist in the greater footprint of the cleanroom facility they each have their own entrance, gowning room, and separate air-handling systems. Forty-five percent of the floorspace of the larger cleanroom is Class 1 (ISO 3), 40 percent of the floorspace is Class 10 (ISO 4), and 15 percent of the floorspace is Class 100 (ISO 5). The biocleanroom has an air cleanliness of Class 1,000 (ISO 6). The BNC cleanroom is one of the largest and cleanest in the U.S. During construction, special attention was paid to airborne and liquidborne contamination control systems within the cleanroom. Air filtering is achieved through an air recirculation system that continuously filters the cleanroom air through Ultra Low Penetration Air filters in the ceiling panels of the cleanroom. There is also an ultra pure water system that removes virtually all contaminates from the process water used for making micro- and nano-structures.
“This clean air and water is extremely important when we build devices and materials at the nanoscale,” says BNC engineering manager Ron Reger. “A dust particle in the air, or micro-organism in our process water, would have a relative scale similar to the Rock of Gibraltar sitting on a small piece of paper.”
The Scifres Nanofabrication Laboratory is named for Purdue alumni Donald and Carol Scifres, who donated $10 million to the construction on BNC. The 187,000-sq. ft. BNC, which opened to researchers in October 2005, involved Purdue faculty, staff, post-docs, and students — graduate and undergraduate — from 27 schools and departments.
The BNC is named for the late Michael and Katherine (Kay) Birck, of Hinsdale, Ill. The Bircks contributed $30 million for the building. A Purdue alumnus, Michael Birck was a member of the Purdue board of trustees and co-founder and chairman of Naperville, Ill.-based Tellabs Inc. Users of the BNC include students, post-docs, and visiting scientists who perform research for over 150 Purdue faculty.
Researchers have access to many traditional semiconductor fabrication tools, including physical vapor deposition, chemical vapor deposition, thermal processing, wet and dry etching, lithography, and numerous metrology tools. In addition, specialized tools such as atomic layer deposition, atomic force microscopes, and e-beam lithography truly make the cleanroom capable of nanoscale fabrication and characterization. Types of fabrication processes used in the cleanroom research include:
• Patterning — Creating nanoscale patterns on wafers with an electron beam, or with specific wavelengths of light.
• Maskmaking — Creating photo masks, which are like photographic negatives in patterning silicon wafers.
• Etching — The transfer of patterns generated with the lithography process into three-dimensional structures.
• Deposition — Depositing films of various materials on surfaces to use in the creation of structures
• Diffusion— Using temperatures of up to 1,200 C to alter the electrical characteristics in specific areas of the silicon wafer.
Undergraduate students contribute to the diverse group of researchers in the facility and are taught to use many of its tools. Undergraduate research projects involve a variety of design, synthesis, fabrication, characterization, and modeling activities. The training they receive during these courses is directly relevant for careers in research and development or production in a number of high-tech fields. In addition, students have a chance to see the facilities used by leading research groups and to interact with graduate students involved in multidisciplinary research projects.
Elizabeth Grubbs of Willmington, Del., a Spring 2015 electrical and computer engineering graduate, used the cleanroom as an undergraduate to gain expertise in her study of integrated nanophotonic circuits and plasmonic metamaterials. She was a student in ECE 557, the only under-graduate class in the nation that uses this level of cleanroom as a laboratory.
“Working in the cleanroom was the single most challenging and rewarding academic experience I had in my entire time as an undergraduate,” says Grubbs. “Not only does it enable individuals to realize their own design in physical devices, it is the single most successful course that teaches non-trivial design.”
Grubbs, who is pursuing her doctoral degree, is working to become the process owner of an experimental setup for Photoluminescent Excitation Spectroscopy (PLE), which is used to measure parameters that are critical for semiconductor devices. PLE allows for the contactless analysis of the surface of a semiconductor, meaning that the same setup can characterize a photovoltaic device as well as evaluate the surface passivation of a semiconductor material.
The research group, led by ECE professor Peter Bermel, is also researching high-performance and multi-junction cells in tandem with the Bay Area Photovoltaic Consortium at Stanford University. The BNC is constantly being updated to ensure that student, faculty, and visiting researchers have access to the cutting edge equipment necessary for continued collaborating and forward movement. The most recent update was completed in June when a section of the laboratory was modified to create a roll-to-roll nanomanufacturing facility. The initiative brings faculty from colleges of Agriculture and Pharmacy to work with colleagues in engineering and sciences and develop next-generation smart pharmaceutical pills, smart sensors for precision agriculture, and smart food labels.
“It is very inspiring and motivating to work alongside the outstanding faculty, students, and staff that develop new discoveries in materials and devices that lead to new applications, devices, and a deeper understanding of nature on the nanoscale,” says Reger. “With their attitudes of curiosity and discovery, as well as the capabilities of the facility, we will continue to do great things, make new discoveries, and develop new devices and technologies for years to come.”
The author wishes to thank Phillip Fiorini for his support and assistance with this article.
Emily Sigg is a writing intern at Purdue Marketing and Media. She can be reached at firstname.lastname@example.org.
This article appeared in the January/February 2016 issue of Controlled Environments.